In many emergency situations, it is critical for a patient to receive prompt and proper attention to his/her injuries in order to avoid exacerbating those injuries that may have already occurred. Often, the first rescuers to arrive on the scene are emergency medical staff who are responsible for preparing the patient for transportation to the nearest medical facility where the individual's injuries are to be treated. Depending upon the particular circumstances surrounding the patient's injuries and the location of an accident scene, these rescuers may be emergency medical squads who are employed with either a fire department, a local hospital, a law enforcement agency, rescue patrols, etc. One of the many concerns of certified rescue workers during their preliminary treatment of a patient is to provide, to the extent possible, the most comfortable surroundings for the individual. This may place the patient at ease and may be vital to the success or failure of initial medical treatment, particularly in instances where weather conditions are severe or where the patient is in shock. For instance, rescues that take place in cold or wet weather conditions, such as those often encountered by ski patrols, require that the patient be adequately insulated from the cold to avoid further reduction in body temperature, while rescues occurring in windy or rainy climates require that the patient be covered with a material repellant to these elements. Therefore, it is vital that the emergency rescue personnel be adequately equipped so that they may quickly and properly adapt to the specific situation at hand.
The patient may remain at the medical facility and require continued thermal protection to provide heat to his/her body. In addition, the patient may be required to undergo a surgical procedure. It is well known that a patient under general anesthesia undergoes several physiological changes that inhibit the body's normal thermoregulatory capabilities. General anesthesia depresses the function of thermoregulating centers in the hypothalamus, thus resulting in the body's diminished ability to self-regulate body temperature. Infusion of intravenous fluid may also contribute to cooling body temperature during surgery because such intravenous fluids absorb heat from the body when they are at a temperature below body temperature. Inspiration of dry anesthesia gases during surgery may also contribute to body temperature cooling during surgery because the dry gas both absorbs heat from the body and because of the cooling action created when water from the body is absorbed by the dry gas. Moreover, during surgery the body cavity may be exposed, which increases the effective surface area of the body and also cools body parts that are normally not exposed to the environment. The incidence of hypothermia occurring after surgery has been estimated to be as great as 60% to 90%. To prevent hypothermia from occurring in many situations, including rescue, emergency surgery, and/or many elective surgeries, it is desired to provide active heating to the patient.
Many conventional devices exist for providing heat. For example, U.S. Pat. No. 6,436,128 to Usui describes an exothermic composition that contains an exothermic substance, a water-absorptive polymer and/or tackifier, a carbon component and/or metal halide, and water. An excessive amount of water is used in the composition to suppress a premature oxidation reaction with air. Once formulated, the exothermic composition of Usui is laminated and sealed in a thin pouch. The pouch absorbs water from the composition so that, when the seal is broken, the exothermic reaction may proceed upon exposure to air and moisture. Despite having some benefits, Usui is simply too complex and difficult to control for most applications.
As such, a need currently exists for an improved thermal covering that is simple, effective, and relatively inexpensive.